Could you use these batteries: http://www.ebay.com/itm/2x-AUTHENTIC-PANASONIC-NCR18650B-3400mAh-Rechargeable-Battery-JAPAN-BUTTON-TOP-/112133708356?hash=item1a1bb09a44:g:IJUAAOSwFe5X1vQR
with this PCB: http://www.batteryspace.com/pcbfor74vli-ionbatterypack8a-1alimit.aspx
and with this...
